Method and semi-product for producing a chip card with a coil

ABSTRACT

The invention describes a method for producing chip cards with contactless and/or contact-type operation having a multilayer card body, an integrated circuit and at least one coil ( 2, 21 ) for data exchange and for power supply. The coil ( 2, 21 ) is applied to one or more layers ( 11 ) of the card body by printing technology, whereby after production of the printed coil a metal foil ( 4, 41 ) is placed over the coil terminals ( 32, 33 ) and laminated into the card body, thereby producing the connection between the contact areas ( 32, 33 ) of the printed coil and the metal foil ( 4, 41 ).

[0001] This invention relates to a method and semifinished product forproducing a chip card having a coil and/or contact areas for contactlessand/or contact-type data exchange with external devices.

[0002] German laid-open print DE 44 16 697 A1 discloses a data carrierand a method for producing a data carrier wherein a coil is disposedwithin a single- or multilayer card structure for the purposes of energysupply and/or data exchange of the integrated circuit with externaldevices. The module comprising the integrated circuit has two contactelements that serve to connect with the contact areas of the coil. Thecoil is preferably a wire-wound coil, punched out of a metal foil orelectroconductive plastic foil or consists of an etched copper coil andis applied to an insulating layer of the card body.

[0003] The electric connection between the contact areas of the coil andthe contact areas of the integrated circuit is produced, or improved, bythe use of conductive adhesive or anisotropic conductive adhesive inknown contacting methods. Alternatively, the contact areas of the coilsand integrated circuit are soldered. Preferably, flip-chip methods areused for this purpose.

[0004] Upon the use of printed coils, which advantageously also haveprinted coil terminal areas, it has turned out that the printed coilsand terminal areas consisting of silver conductive paste do not enterinto a reliable connection with anisotropic conductive adhesive, or thedirect connection of dual interface modules with printed coils involvesreliability problems during production and in operation. The problemtherefore arises of specifying a chip card, a semifinished product and amethod for producing the chip card or semifinished product that permit areliable electric connection between coil and integrated circuit to beproduced using a printed coil.

[0005] This problem is solved starting out from the features of thegeneric part of independent claims 1, 6 and 8 by the characterizingfeatures of said claims.

[0006] Advantageous embodiments of the invention are stated in thedependent claims.

[0007] According to the invention, it is provided that after productionof the printed coil on a carrier element, which can be for example acore foil within the structure of a laminated card, a metal foil isdisposed that at least partly covers the coil terminal areas, a part ofthe metal foil coming to lie opposite the contact areas of the module tobe later incorporated. The layer provided with the printed coil andmetal foil is laminated into the card body. The laminating processpresses the metal foil and the contact areas of the printed coiltogether, thereby producing an electric connection between printed coiland metal foil.

[0008] According to an advantageous embodiment of the invention, it isprovided that conductive adhesive is disposed either on the coil contactareas or on the metal foil in the region of the coil contact areas orover the whole area. The arrangement of the conductive adhesiveincreases the reliability of the electric connection between the coiland the metal foil.

[0009] In particular in case the module is incorporated in the card bodysubsequently, it is provided that a gap is produced in the card body forincorporating the module, said gap being dimensioned so that the metalfoil is exposed in the connecting region to the contact areas of theintegrated circuit. Upon insertion of the module a terminal area for thecoil opposite the contact areas is thus produced.

[0010] According to an advantageous embodiment of the invention, the gapfor the module is milled. In this case it has proved favorable toslightly mill the metal foil in the connecting region to the contactareas of the integrated circuit. In this way a more reliable electricconnection to the contact areas of the integrated circuit is obtainedupon incorporation of the module.

[0011] The electric connection between the metal foil and the terminalareas of the integrated circuit can moreover be improved if ananisotropic conductive adhesive is incorporated between the two terminalareas. In this case the anisotropic conductive adhesive isadvantageously already applied to the terminal areas of the integratedcircuit. Upon lamination of the module into the card body theanisotropic conductive adhesive produces the electric connection withthe metal foil.

[0012] The inventive method permits printed coils to be used incontactless cards or dual interface cards, whereby the reliability ofthe connection between integrated circuit and printed coil can beincreased so that it is comparable to the connection reliability uponthe use of etched copper coils for example.

[0013] The invention relates not only to the method for producing chipcards with contactless and/or contact-type operation but also to asemifinished product to be used for producing said chip cards. Saidsemifinished product consists of a carrier layer on which a printed coilhaving coil terminal areas at the coil ends is disposed. Over each ofsaid coil terminal areas a metal foil is disposed that at least partlycover them and protrude further into the region where the integratedcircuit or module is later to be incorporated.

[0014] Preferably, conductive adhesive is applied to the metal foil orthe coil contact areas in the contacting region to produce a reliableconnection between the metal foil and the coil contact areas. This isadvantageous in particular when the semifinished product, i.e. thecarrier foil with the printed coil and the metal foil, is processed onlylater.

[0015] In addition, the invention relates to a contactlessly operatedchip card or a dual interface card wherein an inside layer of the cardbody has disposed thereon a printed coil whose terminal areas arecovered with a metal foil that is disposed so as to be connected withthe contact areas of the integrated circuit.

[0016] Advantageously, an anisotropic conductive adhesive is disposedbetween the metal foil and the contact areas of the integrated circuit.This has the advantage of increasing the connection reliability and thedurability of the connection.

[0017] Hereinafter the invention will be explained in more detail withreference to FIGS. 1 to 4, in which:

[0018]FIG. 1 shows the front of a dual interface card,

[0019]FIG. 2 shows the back of a dual interface card,

[0020]FIG. 3 shows the layer structure of a dual interface cardaccording to the invention, and

[0021]FIG. 4 shows a cross section of the card according to FIGS. 1, 2and 3.

[0022]FIG. 1 shows the front of chip card 1. It is assumed here that thecover layers are made of transparent material so that the inventiveelements are recognizable.

[0023] Coil 2 with terminal areas 31 and 32 is disposed in core layer 11of card body 1. First coil terminal area 31 is for throughplating tocoil terminal area 31′ of coil 21 located on the back of core foil 11.FIG. 1 shows further terminal area 33 that is likewise throughplated tocoil 21 on the back of the carrier element. Coil contact areas 32 and 33serve to contact the coil with the terminal areas of the integratedcircuit contained in module 5. This connection is effected not directlybut via metal foils 4 or 41 partly covering terminal areas 32 and 33,respectively, and leading to the terminal areas of the integratedcircuit in module 5.

[0024] Metal foils 4 and 41 are preferably made of copper, silver orsilver-plated copper to guarantee good conductivity and reliableconnection.

[0025]FIG. 2 shows the underside of card 1. This side bears the secondpart of coil 21 with terminal areas 31′ and 33′, said terminal areaseach being throughplated to terminal areas 31 and 33 on the front.Terminal area 33 located on the front is shown by dotted lines in FIG.2. As can be seen from FIG. 2, metal foils 4, 41 (FIG. 2 showing backs4′ and 41′) lead to the terminal areas of the integrated circuit, whichare not explicitly shown in the Figure.

[0026]FIG. 3 shows a multilayer card structure in cross section. Saidcard structure consists of carrier foil 11 bearing coil 2 and 2′ (notshown in FIG. 3) with coil terminal areas 31, 32, 33 and 31′, 33′.Disposed over coil terminal areas 32 and 33 is metal foil 4, 4′ which isadvantageously connected with coil terminal areas 32 with anelectroconductive adhesive.

[0027] In the region of the terminal areas of the integrated circuit,anisotropic conductive adhesive 6 is disposed in FIG. 3 for the purposeof connecting with module 5, i.e. terminal areas 7 of module 5. Aconductive adhesive can likewise be disposed between metal foil 4 andcoil terminal areas 32, 33.

[0028]FIG. 4 shows a cross section of a card suitable for contactlessand contact-type data exchange. Module 5 contains an integrated circuitwhich is not shown in the Figure. The integrated circuit can communicatewith the outside world through contact areas 51 by contact-type dataexchange. Contactless data exchange is effected using coil 2, 21, ofwhich only terminal areas 32 and 33 are shown in the Figure. Contactingof coil 2, 21 with terminal areas 7 of the integrated circuit iseffected through metal foils 4, 41 applied to coil terminal areas 32 and33. For contacting it is preferable to use anisotropic conductiveadhesive 6 that is either applied to foil 4, 41 before insertion ofmodule 5, as shown in the Figure, or already disposed on contact areas 7of the integrated circuit.

1. A method for producing chip cards (1) for contactless operation,contact-type operation or a combination thereof, having a multilayercard body, an integrated circuit and at least one coil (2, 21) for dataexchange and for power supply, the coil (2, 21) being applied to one ormore layers (11) of the card body by printing technology, characterizedin that after production of the printed coil a metal foil (4, 41) isplaced over the coil terminals (32, 33) and laminated into the cardbody, thereby producing the connection between the contact areas (32,33) of the printed coil and the metal foil (4, 41).
 2. A methodaccording to claim 1, characterized in that conductive adhesive isdisposed on the coil contact areas (32, 33) or the metal foil (4, 41) inthe region of the coil contact areas (32, 33).
 3. A method according toclaim 1, characterized in that for incorporating a module (5) containingthe integrated circuit, a gap in the card body is produced that isdimensioned so that the metal foil (4, 41) is exposed at least in theconnecting region to the contact areas of the integrated circuit.
 4. Amethod according to claim 3, characterized in that the gap for themodule (5) is milled, the metal foil (4, 41) being exposed or milled atleast in the connecting region to the contact areas of the integratedcircuit.
 5. A method according to claim 1, characterized in that ananisotropic conductive adhesive is disposed between the metal foil (4,41) and the terminal areas of the integrated circuit.
 6. A semifinishedproduct for producing contactlessly operated chip cards (1) having amultilayer card body, an integrated circuit and at least one coil (2,21) for data exchange and for power supply, the coil being applied toone or more layers of the card body by printing technology,characterized in that a printed coil (2, 21) having coil terminal areas(32, 33) that are likewise printed are disposed on a core foil (11) onone or both sides, a metal foil (4, 41) being disposed over the coilterminal areas (32, 33).
 7. A semifinished product according to claim 6,characterized in that the metal foil (4, 41) is connected with the coilterminal areas (32, 33) by conductive adhesive.
 8. A contactlesslyoperated chip card having a multilayer card body, an integrated circuitand at least one coil for data exchange and for power supply, the coilbeing applied to a layer of the card body by printing technology,characterized in that the printed coil (2, 21) is mounted on a core foil(11) of the card body and has coil terminal areas (32, 33) that iscovered by a metal foil (4, 41).
 9. A method according to claim 2,characterized in that for incorporating a module (5) containing theintegrated circuit, a gap in the card body is produced that isdimensioned so that the metal foil (4, 41) is exposed at least in theconnecting region to the contact areas of the integrated circuit.
 10. Amethod according to claim 2, characterized in that an anisotropicconductive adhesive is disposed between the metal foil (4, 41) and theterminal areas of the integrated circuit.
 11. A method according toclaim 3, characterized in that an anisotropic conductive adhesive isdisposed between the metal foil (4, 41) and the terminal areas of theintegrated circuit.
 12. A method according to claim 4, characterized inthat an anisotropic conductive adhesive is disposed between the metalfoil (4, 41) and the terminal areas of the integrated circuit.
 13. Amethod according to claim 9, characterized in that the gap for themodule (5) is milled, the metal foil (4, 41) being exposed or milled atleast in the connecting region to the contact areas of the integratedcircuit.
 14. A method according to claim 9, characterized in that ananisotropic conductive adhesive is disposed between the metal foil (4,41) and the terminal areas of the integrated circuit.
 15. A methodaccording to claim 13, characterized in that an anisotropic conductiveadhesive is disposed between the metal foil (4, 41) and the terminalareas of the integrated circuit.